There are three types of errors in programming: (a) Syntax Errors, (b) Runtime Errors, and (c) Logical Errors. Runtime errors, also called exceptions, occur during execution (after compilation/interpretation). For example, the following line causes a runtime error because here the syntax is correct, but at runtime, it is trying to call a method that does not exist.
<script> <!-- window.printme(); //--> </script>
Exceptions also affect the thread in which they occur, allowing other JavaScript threads to continue normal execution.